Incandescent lamp.



PATENTED JUNE 7, 1904.

S. E. DOANE. INCANDBSGENT LAMP.

APPLIoATIoN FILED DB0. 12, 190s.

N0 MODEL.

nfl-n JJGJ. lui/Gufo?? @oz/vi 80W UNITED STATES Patented June '7, 1904.

PATENT OFFICE.

SAMUEL EVERETT DOANE, OF CLEVELAND, OHIO, ASSIGNOR TO THE NATIONALELECTRIC LAMP COMPANY, OF CLEVELAND, OHIO, A

CORPORATION OF NEINT JERSEY.

INCANDESCENT LAMPl SPECIFICATION forming part of Letters Patent No.762,030, dated June '7, 1904.

Application'lled December l2, 1903. Serial No. 184,914. (No model.)

T 0 (all whom, it 777,047/ @0n/267%:

Be it known that I, SAMUEL EvEnETT DoANE, a citizen of the UnitedStates,residing at Cleveland, in the county of Cuyahoga and State ofOhio, have invented a certain new and useful Improvement in IncandescentLamps, of which the following is a full,clear, and exact description,reference being had to the accompanying drawings.

It is at present the almost universal practice to employ solid platinumwire for the lead-in wires of incandescent lamps. Platinum has twodesirable qualities for lead-in wires not possessed conjointly by anyother metal in any satisfactory degree viz., it is not oxidizable andits coefiicient of expansion is substantially the same as that of glass.It is because it has these qualities that the expensive practice ofusing platinum wire for the purpose specified is continued.

The object of the present invention is to permit the use of lessexpensive wire as the lead-in wires of such lamps.

There are metalsas, for example, certain aluminium-iron alloys-whosecoefficient of expansion is substantially the same as that of certainglass which may be used in making lamp-stems. It has not heretofore beenpossible to use such wire, however, because it oxidizes easily, evenwhen embedded in the glass. IVhen it does oxidize, air will leak inbetween the glass and the oxidized surface ofthe wire into the bulb, andthus destroy the vacuum therein. l have discovered, however, that if onecoats such a wire, as b v electroplating, with a thin skin or shell ofnon-oxidizable metal, as gold, and then seals one or both ends of theshort sections of said wire by fusion such sections may be successfullyused as the lead-in wires of incandescent lamps and analogousstructures. In that case the metal core cannot be oxidized after beingso coated and sealed, or if it were oxidized air could not, because ofthe seal, get bctween'the oxidized surface of the core and thenon-oxidizable coating. Sometimes the core metal in being drawn intowire is not perfectly cylindrical, but, on the contrary, has a crease orfold running longitudinally, as shown in Fig. 3. If such a wire wereelectroplated with gold, for example, and its ends were not scaled, aircould leak between the gold coating and the core through thislongitudinal crease; but if the ends of such wire are sealed by fusionsuch leakage cannot take place. Another kind of coated wire may also beused-to wit, a drawn wire having a metal core and a platinum shell. Suchwire is to be obtained in the open market, and the platinum shell is sothick, comparatively, that it controls the expansion and contraction ofthe wire. By fusing, and thereby sealing one or both ends of shortsections of this wire, leakage of air between the shell and core isprevented and such short sections may be used as the lead-in wires.

My invention therefore is adapted for use with coated wires of eithertype referred to; and it consists in the employment as the leadin wiresof incandescent lamps and analogous devices of wire having a metalliccore and a non-oxidizable coating and having one or both of its endssealed by fusion. It also consists of an incandescent lamp in which suchlead-in wires are employed, and also in the more speciiic details ofconstruction hereinafter set forth, and definitely pointed out in theclaims.

In the drawings, Figure 1 is a longitudinal sectional view of anincandescent lamp cmbodying the present invention. Fig. 2 is an enlargedsectional view of a portion of the glass end Aof the lamp-stem, in whichglass end is embedded the joint between a conductorwire and a coatedlead-in wire having its ends sealed by fusion. Fig. 3 is a very muchenlarged section of a wire having a creased core and an outer coating ofnon-oxidizable metal electroplated thereon.

A represents the lamp-bulb, and B the glass stem thereof.

C C represent the conductor-wires, which are usually made of copper, andD the coated lead-in wires. The coating thereof is not oxidizable. Inpreparing these lead-in wires for use proper lengths thereof are severedfrom the spool, preferably by electrically fusing' them off. By thismethod of procedure the ends of the severed sections are melted and thenwhen cool they close the ends of the tubular platinum shell andeifectually prevent any access of air between it and the metal core. Itis of course apparent that these leadin wires may be cut 0E land thentheir ends may be fused electrically on a blowpipe-ame, therebyattaining the same desirable result. There is, however, a distinctadvantage in severing them electrically. as stated, because it issubstantially as cheap a method of procedure as it is to cut them off,and thereby both ends of the short lead-in wires are effectually sealed.This is adesirable precautionary condition and is attained without anyadditional expense. If by chance one end were not perfectly sealed bythe fusion and the other end were, access of air to the bulb between thecoating and core of a lead-in wire will be prevented. In using thesecoated lead-in wires having their ends sealed as stated theconductor-wires may be connected thereto in the usual manner or anysuitable manner, as by what is known in this art as welding. The jointbetween the conductor-wires and leadin wires and short adjacent portionsof said wires are then embedded in the glass of the end of the stem inthe usual manner. It is obvious that this manner of providing forelectrical connections between the interior of a vacuum-tube and theexterior thereof may be employed in connection with various devicesanalogous to incandescent lamps.

Having described my invention, I claim- 1. In an electric lamp,a lead-inwire havinga metallic core and a non-oxidizable metallic coating, oneend of said wire being sealed by fusion.

Q. In an electric lamp,alead-in wirehavinga metallic core and anon-oxidizable metallic coating, both ends of said wire being sealed byfusion.

3. In an electric lamp,a lead-in wire having a metallic core and anon-oXidiZable metallic coating, the outer end of said wire being sealedby fusion, combined with a conductor-wire fastened to said lead-in wire,and the lampstem, in the closed glass end of which the joint betweensaid wires is embedded.

In testimony whereofl I hereunto affix my signature in the presence oftwo witnesses.

SAMUEL EVERETT DOANE.

' W'itnesses:

E. L. THURsToN, B. W. BROCKETT.

